安德-谷歌地图获取当前位置

Question

我正在开发一个应用程序，我需要在地图上显示我的当前位置。不幸的是，我得到了错误：

第53行：

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.vojtechadam.mcdonaldscoupons, PID: 8329
java.lang.NullPointerException: Attempt to invoke virtual method 'double android.location.Location.getLatitude()' on a null object reference
at com.example.mcdonaldscoupons.MapFragment.onMapReady(MapFragment.java:53)
at com.google.android.gms.maps.zzat.zzb(com.google.android.gms:play-services-maps@@17.0.1:1)
at com.google.android.gms.maps.internal.zzaq.zza(com.google.android.gms:play-services-maps@@17.0.1:6)
at com.google.android.gms.internal.maps.zzb.onTransact(com.google.android.gms:play-services-maps@@17.0.1:3)
at android.os.Binder.transact(Binder.java:1043)
at dp.aZ(:com.google.android.gms.dynamite_mapsdynamite@212116097@21.21.16 (150400-0):2)
at com.google.maps.api.android.lib6.impl.bk.run(:com.google.android.gms.dynamite_mapsdynamite@212116097@21.21.16 (150400-0):1)
at android.os.Handler.handleCallback(Handler.java:938)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:7861)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:600)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
I/Process: Sending signal. PID: 8329 SIG: 9

我的onRequestPermissionResult也不起作用。。。我想在导航抽屉中点击我的地图片段时将请求发送到位置，但上面写着这个

第80行：覆盖"androidx.fragment.app.fragment"中不推荐使用的方法

第81行："onRequestPermissionsResult(int，java.lang.String[]，int[]("已弃用

MapFragment.java

public class MapFragment extends Fragment implements OnMapReadyCallback {
Location currentLocation;
FusedLocationProviderClient fusedLocationProviderClient;
private static final int REQUEST_CODE = 101;
@Nullable
@org.jetbrains.annotations.Nullable
@Override
public View onCreateView(@NonNull @NotNull LayoutInflater inflater, @Nullable @org.jetbrains.annotations.Nullable ViewGroup container, @Nullable @org.jetbrains.annotations.Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_map, container, false);
}
@Override
public void onViewCreated(@NonNull View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(getActivity());
fetchLastLocation();
SupportMapFragment supportMapFragment = (SupportMapFragment)
getChildFragmentManager().findFragmentById(R.id.google_map);
supportMapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
LatLng latLng = new LatLng(currentLocation.getLatitude(), currentLocation.getLongitude());
MarkerOptions markerOptions = new MarkerOptions().position(latLng)
.title("Here I am!");
googleMap.animateCamera(CameraUpdateFactory.newLatLng(latLng));
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 5));
googleMap.addMarker(markerOptions);
}
private void fetchLastLocation() {
if (ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(getActivity(), new String[]
{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_CODE);
return;
}
Task<Location> task = fusedLocationProviderClient.getLastLocation();
task.addOnSuccessListener(location -> {
if (location != null) {
currentLocation = location;
Toast.makeText(getContext(), currentLocation.getLatitude()
+ "" + currentLocation.getLongitude(), Toast.LENGTH_SHORT).show();
SupportMapFragment supportMapFragment = (SupportMapFragment)
getChildFragmentManager().findFragmentById(R.id.google_map);
supportMapFragment.getMapAsync(MapFragment.this);
}
});
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull @NotNull String[] permissions, @NonNull @NotNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode) {
case REQUEST_CODE:
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
fetchLastLocation();
}
break;
}
}
}

Answer 1

您正在Ready上设置当前位置标记。但你应该在得到位置后再做。检查下面的代码。

private GoogleMap googleMap;

@Override
public void onMapReady(GoogleMap googleMap) {
this.googleMap = googlemap;
}
private void fetchLastLocation() {
if (ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(getActivity(), new String[]
{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_CODE);
return;
}
Task<Location> task = fusedLocationProviderClient.getLastLocation();
task.addOnSuccessListener(location -> {
if (location != null) {
currentLocation = location;
UpdateCurrentLocation();
Toast.makeText(getContext(), currentLocation.getLatitude()
+ "" + currentLocation.getLongitude(), Toast.LENGTH_SHORT).show();
SupportMapFragment supportMapFragment = (SupportMapFragment)
getChildFragmentManager().findFragmentById(R.id.google_map);
supportMapFragment.getMapAsync(MapFragment.this);
}
});
}
private void UpdateCurrentLocation() {
LatLng latLng = new LatLng(currentLocation.getLatitude(), 
currentLocation.getLongitude());
MarkerOptions markerOptions = new MarkerOptions().position(latLng)
.title("Here I am!");
googleMap.animateCamera(CameraUpdateFactory.newLatLng(latLng));
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 5));
googleMap.addMarker(markerOptions);
}